Site Editor

William J. Gradishar, MD, FACP, FASCO


Can Addition of T-DM1 Improve Outcomes Over Standard Treatment in HER2-Positive Breast Cancer?

By: Vanessa A. Carter, BS
Posted: Thursday, May 5, 2022

The phase III KAITLIN study, conducted by Ian E. Krop, MD, of the Dana-Farber Cancer Institute, Harvard Medical School, Boston, and colleagues aimed to improve the efficacy and safety of treatment for high-risk HER2-positive breast cancer by replacing taxanes and trastuzumab with trastuzumab emtansine (T-DM1). Published in the Journal of Clinical Oncology, these results concluded that although both arms reached a favorable invasive disease–free survival, the combination of trastuzumab, pertuzumab, and chemotherapy remains the standard of care for this disease.

This multinational, open-label trial enrolled 1,846 adults with excised HER2-positive early breast cancer with node-positive (n = 1,658) disease. Participants were randomly assigned to receive three to four cycles of anthracycline-based chemotherapy and then 18 cycles of T-DM1 plus pertuzumab (AC-KP; n = 928), or three to four cycles of taxane plus trastuzumab plus pertuzumab (AC-THP; n = 918). Adjuvant endocrine therapy and/or radiotherapy was allowed.

At the median follow-up of 57.1 months for AC-THP and 57.0 months for AC-KP, there appeared to be no significant difference in invasive disease–free survival between the node-positive group (hazard ratio [HR] = 0.97) and the overall (HR = 0.98) population. Of note, the 3-year invasive disease–free survival rates were also similar among patients in the overall population who received AC-THP (94.2%) or AC-KP (93.1%).

The treatment completion rate was higher among patients administered AC-THP versus AC-KP (88.4% vs. 65.0%), which was thought to be due to laboratory abnormalities leading to T-DM1 discontinuation. Notably, both the AC-THP and AC-KP treatment arms experienced similar rates of grade 3 or higher adverse events (55.4% vs. 51.8%) or adverse events considered to be serious (23.3% vs. 21.4%). Furthermore, treatment with T-DM1 plus pertuzumab was observed to decrease clinically meaningful deterioration in global health status versus the combination of taxane, trastuzumab, and pertuzumab (HR = 0.71).

Disclosure: For full disclosures of the study authors, visit

By continuing to browse this site you permit us and our partners to place identification cookies on your browser and agree to our use of cookies to identify you for marketing. Read our Privacy Policy to learn more.